Atherectomy devices and methods

ABSTRACT

Rotational atherectomy devices and systems can remove or reduce stenotic lesions in implanted grafts by rotating one or more abrasive elements within the graft. The abrasive elements can be attached to a distal portion of an elongate flexible drive shaft that extends from a handle assembly that includes a driver for rotating the drive shaft. In particular implementations, individual abrasive elements are attached to the drive shaft at differing radial angles in comparison to each other (e.g., configured in a helical array). The centers of mass of the abrasive elements can define a path that fully or partially spirals around the drive shaft.

TECHNICAL FIELD

This document relates to rotational atherectomy devices and systems forremoving or reducing stenotic lesions in blood vessels and/orarteriovenous grafts, for example, by rotating an abrasive elementwithin the vessel to partially or completely remove the stenotic lesionmaterial.

BACKGROUND

Blood flow through the peripheral arteries (e.g., iliac, femoral, renaletc.), can be affected by the development of atherosclerotic blockages.Peripheral artery disease (PAD) can be serious because without adequateblood flow, the kidneys, legs, arms, and feet may suffer irreversibledamage. Left untreated, the tissue can die or harbor infection.

Patients that have kidneys that do not function properly may requirehemodialysis to purify the blood of the patient. To gain access to theblood for hemodialysis, an arteriovenous fistula or a graft can be usedto connect an artery and a vein. Similar to blood vessels, fistulasand/or grafts can become clogged with plaque.

SUMMARY

This document relates to rotational atherectomy devices, systems, andmethods for removing or reducing stenotic lesions in an implanted graft(e.g., a synthetic arteriovenous (AV) graft) by rotating one or moreabrasive elements to abrade and breakdown the lesion. Vascular accessstenosis is a common issue found in hemodialysis patients. In variousembodiments, a graft can be implanted into a hemodialysis patient toaccess blood vessels capable of providing rapid extracorporeal bloodflow during hemodialysis. The implanted graft may be prone to vascularaccess stenosis, which forms fibrous plaque-like lesions within thelumen of the graft and extending into the native artery and veinattached to the graft. Stenotic lesions that typically develop inassociation with the implanted graft can contain non-calcifiedneointimal hyperplasia and may lead to thrombosis and graft occlusion.

Some embodiments of the systems and devices provided herein can abradestenotic lesions in the grafts by rotating the abrasive element(s)according to a stable and predictable orbiting profile. In someembodiments, the abrasive element(s) are attached to a distal portion ofan elongate flexible drive shaft that extends from a handle assembly. Inparticular embodiments, a rotational atherectomy device comprises anelongate flexible drive shaft with multiple eccentric abrasive elementsthat are attached to the drive shaft, and one or more stability elementsare attached to the drive shaft such that at least one stability elementis distal of the abrasive element. Optionally, the stability elementshave a center of mass that are axially aligned with a centrallongitudinal axis of the drive shaft while the eccentric abrasiveelement(s) has(have) a center(s) of mass that is(are) axially offsetfrom central longitudinal axis of the drive shaft.

In some embodiments, multiple abrasive elements are coupled to the driveshaft and are offset from each other around the drive shaft such thatthe centers of the abrasive elements are disposed at differing radialangles from the drive shaft in relation to each other. For example, insome embodiments a path defined by the centers of mass of the abrasiveelements defines a spiral around a length of the central longitudinalaxis of the drive shaft. A flexible polymer coating may surround atleast a portion of the drive shaft, including the stability element(s)in some embodiments. Also, in some optional embodiments, a distalextension portion of the drive shaft may extend distally beyond thedistal-most stability element.

In one aspect, this disclosure is directed to a method for performingrotational atherectomy to remove stenotic lesion material from anarteriovenous graft of a patient. The method includes delivering arotational atherectomy device into the arteriovenous graft. Therotational atherectomy device includes an elongate flexible drive shaftthat includes a torque-transmitting coil and defines a longitudinalaxis, the drive shaft being configured to rotate about the longitudinalaxis, and a helical array of abrasive elements attached to a distal endportion of the drive shaft, each of the abrasive elements having acenter of mass that is offset from the longitudinal axis, the centers ofmass of the abrasive elements arranged along a path that spirals aroundthe longitudinal axis. The method further includes rotating the driveshaft about the longitudinal axis such that the abrasive elements orbitaround the longitudinal axis.

In another aspect, this disclosure is directed to a method forperforming rotational atherectomy to remove stenotic lesion materialfrom an arteriovenous graft of a patient. The method can includedelivering a rotational atherectomy device into the arteriovenous graft.The rotational atherectomy device can include an elongate flexible driveshaft that includes a torque-transmitting coil and defines alongitudinal axis, the drive shaft being configured to rotate about thelongitudinal axis, and first and second abrasive elements attached to adistal end portion of the drive shaft and each having a center of massoffset from the longitudinal axis, the center of mass of the firstabrasive element being offset from the longitudinal axis at a firstradial angle, the center of mass of the second abrasive element beingoffset from the longitudinal axis at a second radial angle that differsfrom the first radial angle. The method further includes rotating thedrive shaft about the longitudinal axis such that the abrasive elementsorbit around the longitudinal axis.

One or more of the methods can further include the embodiments describedherein. In some embodiments, the method can include translationallymoving the drive shaft along the longitudinal axis. The method caninclude modifying a speed of the drive shaft. Modifying the speed of thedrive shaft can include modifying a diameter of rotation. In someembodiments, delivering the rotational atherectomy device can includedelivering the rotational atherectomy device with a distal portion ofthe rotational atherectomy device positioned toward a vein of thepatient. Delivering the rotational atherectomy device can includedelivering the rotational atherectomy device with a distal portion ofthe rotational atherectomy device positioned toward an artery of thepatient to treat a lesion at an arterial anastomosis. In someembodiments, the method can further include inflating an inflatablemember on the rotational atherectomy device. In some embodiments, therotational atherectomy device can further include a distal stabilityelement affixed to the drive shaft and having a center of mass alignedwith the longitudinal axis, the distal stability element distally spacedapart from the plurality of abrasive elements.

In yet another aspect, this disclosure is directed to a device forperforming rotational atherectomy to remove stenotic lesion materialfrom an arteriovenous graft of a patient. The device includes means forcausing rotation along a longitudinal axis of the device, a first meansfor removing stenotic lesion material from the arteriovenous graft ofthe patient, the first means having a first center of mass offset fromthe longitudinal axis at a first radial angle, a second means forremoving stenotic lesion material from the arteriovenous graft of thepatient, the second means having a second center of mass offset from thelongitudinal axis at a second radial angle that differs from the firstradial angle, and means for mounting the means for transmitting, thefirst means, and the second means.

In some embodiments, the device can further include a third means forremoving stenotic lesion material from the arteriovenous graft of thepatient, the third means having a third center of mass offset from thelongitudinal axis at a third radial angle that differs from the firstradial angle and the second radial angle. In some embodiments, thesecond radial angle differs from the first radial angle by at least 15degrees, and the third radial angle differs from the first radial angleand the second radial angle by at least 15 degrees. In some embodiments,a proximal-most one of the means for removing stenotic lesion materialand a distal-most means for removing stenotic lesion material are eachsmaller than intermediate ones of the means for removing stenotic lesionmaterial. In some embodiments, the means for stabilizing include meansfor removing stenotic lesion material. In some embodiments, the devicefurther includes means for receiving a guidewire along the longitudinalaxis. In some embodiments, the device also includes means for causingtranslational movement of the device along the longitudinal axis. Insome embodiments, the device includes means for extending a distalportion of the device. In some embodiments, the device further includesmeans for stabilizing the means for mounting, the means for stabilizinghaving a center of mass aligned with the longitudinal axis.

Some of the embodiments described herein may provide one or more of thefollowing advantages. First, some embodiments of the rotationalatherectomy devices and systems operate with a stable and predictablerotary motion profile for an atherectomy procedure applied to animplanted graft (e.g., synthetic AV graft) for the removal of stenoticplaque-like lesions from within the graft. That is, when the device isbeing rotated in operation, the eccentric abrasive element(s) follows apredefined, consistent orbital path (offset from an axis of rotation ofthe device) while the stability element(s) and other portions of thedevice remain on or near to the axis of rotation for the drive shaft ina stable manner. This predictable orbital motion profile can be attainedby the use of design features including, but not limited to, stabilityelement(s) that have centers of mass that are coaxial with thelongitudinal axis of the drive shaft, a polymeric coating on at least aportion of the drive shaft, a distal-most drive shaft extension portion,and the like. Some embodiments of the rotational atherectomy devices andsystems provided herein may include one or more of such design features.

Second, the rotational atherectomy devices provided herein may include adistal stability element that has an abrasive outer surface that allowsa rotational atherectomy device, when being advanced within an implantedgraft, to treat plaque-like lesions that occlude or substantiallyocclude the graft. In such applications, the abrasive outer surface onthe distal stability element may help facilitate passage of the distalstability element through plaque-like lesions that occlude orsubstantially occlude the graft. In some such cases, the drive shaft maybe used to rotate the distal stability element to help facilitate boringof the distal stability element through such lesions in a drill-likefashion.

Third, some embodiments of the rotational atherectomy devices andsystems provided herein can be used to treat various graft sizes (e.g.,large-diameter grafts having an internal diameter that is multiple timegreater than the outer diameter of the abrasive element) while, in someembodiments, using a small introducer sheath size for delivery of thedevices and systems. In other words, in some embodiments the rotatingeccentric abrasive element(s) traces an orbital path that issubstantially larger than the outer diameter of the rotationalatherectomy device in the non-rotating state. This feature improves theability of the rotational atherectomy devices provided herein to treat,in some embodiments, very large grafts while still fitting within asmall introducer size. In some embodiments, this feature can be at leastpartially attained by using a helical array of abrasive elements thathas a high eccentric mass (e.g., the centers of mass of the abrasiveelements are significantly offset from the central longitudinal axis ofthe drive shaft). Further, in some embodiments this feature can be atleast partially attained by using multiple abrasive elements that areradially offset from each other around the drive shaft such that thecenters of the abrasive elements are not coaxial with each other.

Fourth, in some embodiments rotational atherectomy systems describedherein include user controls that are convenient and straight-forward tooperate. In one such example, the user controls can include selectableelements that correspond to the diametric size of the implanted graft(s)to be treated. When the clinician-user selects the particular graftsize, the system will determine an appropriate rpm of the drive shaft toobtain the desired orbit of the abrasive element(s) for the particulargraft size. Hence, in such a case the clinician-user conveniently doesnot need to explicitly select or control the rpm of the drive shaft. Inanother example, the user controls can include selectable elements thatcorrespond to the speed of drive shaft rotations. In some such examples,the user can conveniently select “low,” “medium,” or “high” speeds.

The details of one or more embodiments of the invention are set forth inthe accompanying drawings and the description below. Other features,objects, and advantages of the invention will be apparent from thedescription and drawings, and from the claims.

DESCRIPTION OF DRAWINGS

FIG. 1 shows an example rotational atherectomy system that is being usedto perform a rotational atherectomy procedure in an arm of a patient.

FIG. 2 shows the example rotational atherectomy device of FIG. 1 withina region of a lesion in a graft located in an arm of a patient.

FIG. 3 shows the example rotational atherectomy device of FIG. 1 withina region of a lesion in a graft located in an arm of a patient.

FIG. 4 shows the example rotational atherectomy device of FIG. 1 withina region of a lesion in a graft located in a chest of a patient.

FIG. 5 shows the example rotational atherectomy device of FIG. 1 withina region of a lesion in a graft located in a torso of a patient.

FIG. 6 shows an example user control unit of a rotational atherectomysystem being operated by a clinician-user to perform a rotationalatherectomy procedure above the knee of a patient.

FIG. 7 shows the example rotational atherectomy device of FIG. 1 withinthe region of the lesion.

FIG. 8 shows the rotational atherectomy device of FIG. 1 with theabrasive element being rotated with a first diameter of orbit at a firstlongitudinal position.

FIG. 9 shows the rotational atherectomy device of FIG. 1 with theabrasive element being rotated with a second diameter of orbit at thefirst longitudinal position.

FIG. 10 shows the rotational atherectomy device of FIG. 1 with theabrasive element being rotated with the second diameter of orbit at asecond longitudinal position.

FIG. 11 shows the example rotational atherectomy device of FIG. 1 in useat a first longitudinal position in the region of the lesion. Amulti-portion abrasive element of the rotational atherectomy device isbeing rotated along an orbital path to abrade the lesion.

FIG. 12 shows the rotational atherectomy device of FIG. 1 with theabrasive element being rotated at a second longitudinal position that isdistal of the first longitudinal position.

FIG. 13 shows the rotational atherectomy device of FIG. 1 with theabrasive element being rotated at a third longitudinal position that isdistal of the second longitudinal position.

FIG. 14 is a longitudinal cross-sectional view of a distal portion of anexample rotational atherectomy device showing a multi-portion abrasiveelement and a distal stability element with an abrasive coating.

FIG. 15 is a side view of a distal portion of another example rotationalatherectomy device showing a multi-portion abrasive element and a distalstability element with an abrasive coating. The individual portions ofthe multi-portion abrasive element are offset from each other around thedrive shaft such that the centers of mass of the abrasive elementportions define a spiral path around the drive shaft axis.

FIG. 16 is a transverse cross-sectional view of the rotationalatherectomy device of FIG. 15 taken along the cutting-plane line 16-16.

FIG. 17 is a transverse cross-sectional view of the rotationalatherectomy device of FIG. 15 taken along the cutting-plane line 17-17.

FIG. 18 is a transverse cross-sectional view of the rotationalatherectomy device of FIG. 15 taken along the cutting-plane line 18-18.

FIG. 19 is a transverse cross-sectional view of the rotationalatherectomy device of FIG. 15 taken along the cutting-plane line 19-19.

FIG. 20 is a transverse cross-sectional view of the rotationalatherectomy device of FIG. 15 taken along the cutting-plane line 20-20.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Referring to FIG. 1, in some embodiments a rotational atherectomy system100 for removing or reducing stenotic lesions in implanted grafts 32(e.g., a synthetic AV graft) can include a rotational atherectomy device170 and a controller 150. In some embodiments, the rotationalatherectomy device 170 can include a guidewire 134, an actuator handleassembly 110, and an elongate flexible drive shaft assembly 130. Thedrive shaft assembly 130 extends distally from the handle assembly 110.The controller 150 can be connected to the handle assembly 110 via acable assembly 160. The handle assembly 110 and controller 150 can beoperated by a clinician to perform and control the rotationalatherectomy procedure. In some embodiments, the actuator handle assembly110 can be an electric handle that includes an electric motor, and caninclude speed controls, actuator buttons, and other functions to performand control the rotational atherectomy procedure.

In the depicted embodiment, the elongate flexible drive shaft assembly130 includes a sheath 132 and a flexible drive shaft 136. A proximal endof the sheath 132 is fixed to a distal end of the handle assembly 110.The flexible drive shaft 136 is slidably and rotatably disposed within alumen of the sheath 132. The flexible drive shaft 136 defines alongitudinal lumen in which the guidewire 134 is slidably disposed. Asdepicted, the flexible drive shaft 136 includes a torque-transmittingcoil that defines the longitudinal lumen along a central longitudinalaxis, and the drive shaft 136 is configured to rotate about thelongitudinal axis while the sheath 132 remains generally stationary.Hence, as described further below, during a rotational atherectomyprocedure the flexible drive shaft 136 is in motion (e.g., rotating andlongitudinally translating) while the sheath 132 and the guidewire 134are generally stationary.

The rotational atherectomy device 170 can include one or more abrasiveelements 138 that are eccentrically-fixed to the drive shaft 136proximal of a distal stability element 140. In some embodiments, thedistal stability element 140 is concentrically-fixed to the drive shaft136 between the one or more abrasive elements 138 and a distal driveshaft extension portion. As such, the center of mass of the distalstability element 140 is aligned with the central axis of the driveshaft 136 while the center of mass of each abrasive element 138 isoffset from the central axis of the drive shaft 136.

Still referring to FIG. 1, the graft 32 to be treated is in an arm 12 ofa patient 10. For example, the graft 32 may be located below an elbow ofthe patient 10. In the depicted example, the graft 32 is a loop graft32. In some embodiments, the distal portion of the rotationalatherectomy device 170 is introduced into the vasculature by penetratingthrough a wall of the graft 32. In some embodiments, the graft 32 may beconnecting a radial artery or a brachial artery 34 to a median cubitalvein or a basilic vein 36. As shown in the depicted embodiment, therotational atherectomy device 170 is inserted such that a distal portionof the rotational atherectomy device 170 is pointed toward a venousvessel, such as a median cubital or basilic vein 36. The abrasiveelements 138 on the drive shaft 136 of the rotational atherectomy device170 can be rotated to remove one or more lesions in the graft 32.

In some embodiments, the graft 32 is a self-healing graft, such thatpunctures in the graft caused by insertion of the rotational atherectomydevice 170 will close and heal without additional aid. In someembodiments, the graft 32 can have an outer diameter of from about 4millimeters (mm) to about 8 mm.

Referring to FIG. 2, in another example, the graft 32 to be treated isin an arm 12 of a patient 10. For example, the graft 32 may be locatedbelow an elbow of the patient 10. In the depicted example, the graft 32is a straight graft 32. In some embodiments, the graft 32 may beconnecting a radial artery 34 to one of a median cubital vein, a basilicvein, or a cephalic vein 36. In some embodiments, the rotationalatherectomy device 170 can be inserted such that a distal portion of therotational atherectomy device 170 is pointed toward the median cubitalvein, the basilic vein, or the cephalic vein 36. The abrasive elementson the rotational atherectomy device 170 can be rotated to remove alesion in the graft 32.

Referring to FIG. 3, in some embodiments, the graft 32 to be treated isin an arm 12 of a patient 10. For example, the graft 32 may be locatedbelow an elbow of the patient 10. In some examples, the graft 32 is aloop graft 32. In some embodiments, the graft 32 may be connecting aradial artery or a brachial artery 34 to a median cubital vein or abasilic vein 36. In some embodiments, the rotational atherectomy device170 can be inserted such that a distal portion of the rotationalatherectomy device 170 is pointed toward the median cubital vein or thebasilic vein 36. The abrasive elements on the rotational atherectomydevice 170 can be rotated to remove a lesion in the graft 32.

Referring to FIG. 4, in some examples, the graft 32 to be treated is ina torso 14 of a patient 10. For example, the graft 32 may be locatedacross a chest of the patient 10. In some embodiments, the graft 32 maybe connecting an axillary artery 34 to an axillary vein 36. In thedepicted embodiment, the rotational atherectomy device 170 can beinserted such that a distal portion of the rotational atherectomy device170 is pointed toward the axillary vein 36. The abrasive elements on therotational atherectomy device 170 can be rotated to remove a lesion inthe graft 32.

Referring to FIG. 5, in some examples, the graft 32 to be treated is ina torso 14 of a patient 10. In some embodiments, the graft 32 may beconnecting an axillary artery 34 to a saphenous vein 36 of the patient10. In the depicted embodiment, the rotational atherectomy device 170can be inserted such that a distal portion of the rotational atherectomydevice 170 is pointed toward the saphenous vein 36. The abrasiveelements on the rotational atherectomy device 170 can be rotated toremove a lesion in the graft 32.

Referring back to FIG. 1, in some optional embodiments, an inflatablemember (not shown) can surround a distal end portion of the sheath 132.Such an inflatable member can be selectively expandable between adeflated low-profile configuration and an inflated deployedconfiguration. The sheath 132 may define an inflation lumen throughwhich the inflation fluid can pass (to and from the optional inflatablemember). The inflatable member can be in the deflated low-profileconfiguration during the navigation of the drive shaft assembly 130through the patient's graft to a target location. Then, at the targetlocation, the inflatable member can be inflated so that the outerdiameter of the inflatable member contacts the wall of the vessel. Inthat arrangement, the inflatable member advantageously stabilizes thedrive shaft assembly 130 in the vessel during the rotational atherectomyprocedure.

Still referring to FIG. 1, the flexible drive shaft 136 is slidably androtatably disposed within a lumen of the sheath 132. A distal endportion of the drive shaft 136 extends distally of the distal end of thesheath 132 such that the distal end portion of the drive shaft 136 isexposed (e.g., not within the sheath 132, at least not during theperformance of the actual rotational atherectomy).

In the depicted embodiment, the exposed distal end portion of the driveshaft 136 includes one or more abrasive elements 138, a (optional)distal stability element 140, and a distal drive shaft extension portion142. In the depicted embodiment, the one or more abrasive elements 138are eccentrically-fixed to the drive shaft 136 proximal of the distalstability element 140. In this embodiment, the distal stability element140 is concentrically-fixed to the drive shaft 136 between the one ormore abrasive elements 138 and the distal drive shaft extension portion142. As such, the center of mass of the distal stability element 140 isaligned with the central axis of the drive shaft 136 while the center ofmass of each abrasive element 138 is offset from the central axis of thedrive shaft 136. The distal drive shaft extension portion 142, whichincludes the torque-transmitting coil, is configured to rotate about thelongitudinal axis extends distally from the distal stability element 140and terminates at a free end of the drive shaft 136.

In some optional embodiments, a proximal stability element (not shown)is included. The proximal stability element can be constructed andconfigured similarly to the depicted embodiment of the distal stabilityelement 140 (e.g., a metallic cylinder directly coupled to thetorque-transmitting coil of the drive shaft 136 and concentric with thelongitudinal axis of the drive shaft 136) while being located proximalto the one or more abrasive elements 138.

In the depicted embodiment, the distal stability element 140 has acenter of mass that is axially aligned with a central longitudinal axisof the drive shaft 136, while the one or more abrasive elements 138(collectively and/or individually) have a center of mass that is axiallyoffset from central longitudinal axis of the drive shaft 136.Accordingly, as the drive shaft 136 is rotated about its longitudinalaxis, the principle of centrifugal force will cause the one or moreabrasive elements 138 (and the portion of the drive shaft 136 to whichthe one or more abrasive elements 138 are affixed) to follow atransverse generally circular orbit (e.g., somewhat similar to a “jumprope” orbital movement) relative to the central axis of the drive shaft136 (as described below, for example, in connection with FIGS. 11-13).In general, faster speeds (rpm) of rotation of the drive shaft 136 willresult in larger diameters of the orbit (within the limits of the graftdiameter). The orbiting one or more abrasive elements 138 will contactthe stenotic lesion to ablate or abrade the lesion to a reduced size(i.e., small particles of the lesion will be abraded from the lesion).

The rotating distal stability element 140 will remain generally at thelongitudinal axis of the drive shaft 136 as the drive shaft 136 isrotated (as described below, for example, in connection with FIGS.11-13). In some optional embodiments, two or more distal stabilityelements 140 are included. As described further below, contemporaneouswith the rotation of the drive shaft 136, the drive shaft 136 can betranslated back and forth along the longitudinal axis of the drive shaft136. Hence, lesions can be abraded radially and longitudinally by virtueof the orbital rotation and translation of the one or more abrasiveelements 138, respectively.

The flexible drive shaft 136 of rotational atherectomy system 100 islaterally flexible so that the drive shaft 136 can readily conform tothe non-linear grafts of the patient, and so that a portion of the driveshaft 136 at and adjacent to the one or more abrasive elements 138 willlaterally deflect when acted on by the centrifugal forces resulting fromthe rotation of the one or more eccentric abrasive elements 138. In thisembodiment, the drive shaft 136 comprises one or more helically woundwires (or filars) that provide one or more torque-transmitting coils ofthe drive shaft 136 (as described below, for example, in connection withFIGS. 14-15). In some embodiments, the one or more helically wound wiresare made of a metallic material such as, but not limited to, stainlesssteel (e.g., 316, 316L, or 316LVM), nitinol, titanium, titanium alloys(e.g., titanium beta 3), carbon steel, or another suitable metal ormetal alloy. In some alternative embodiments, the filars are or includegraphite, Kevlar, or a polymeric material. In some embodiments, thefilars can be woven, rather than wound. In some embodiments, individualfilars can comprise multiple strands of material that are twisted,woven, or otherwise coupled together to form a filar. In someembodiments, the filars have different cross-sectional geometries (sizeor shape) at different portions along the axial length of the driveshaft 136. In some embodiments, the filars have a cross-sectionalgeometry other than a circle, e.g., an ovular, square, triangular, oranother suitable shape.

In this embodiment, the drive shaft 136 has a hollow core. That is, thedrive shaft 136 defines a central longitudinal lumen runningtherethrough. The lumen can be used to slidably receive the guidewire134 therein, as will be described further below. In some embodiments,the lumen can be used to aspirate particulate or to convey fluids thatare beneficial for the atherectomy procedure.

In some embodiments, the drive shaft 136 includes an optional coating onone or more portions of the outer diameter of the drive shaft 136. Thecoating may also be described as a jacket, a sleeve, a covering, acasing, and the like. In some embodiments, the coating adds columnstrength to the drive shaft 136 to facilitate a greater ability to pushthe drive shaft 136 through stenotic lesions. In addition, the coatingcan enhance the rotational stability of the drive shaft 136 during use.In some embodiments, the coating is a flexible polymer coating thatsurrounds an outer diameter of the coil (but not the abrasive elements138 or the distal stability element 140) along at least a portion ofdrive shaft 136 (e.g., the distal portion of the drive shaft 136 exposedoutwardly from the sheath 132). In some embodiments, a portion of thedrive shaft 136 or all of the drive shaft 136 is uncoated. In particularembodiments, the coating is a fluid impermeable material such that thelumen of the drive shaft 136 provides a fluid impermeable flow pathalong at least the coated portions of the drive shaft 136.

The coating may be made of materials including, but not limited to,PEBEX, PICOFLEX, PTFE, ePTFE, FEP, PEEK, silicone, PVC, urethane,polyethylene, polypropylene, and the like, and combinations thereof. Insome embodiments, the coating covers the distal stability element 140and the distal extension portion 142, thereby leaving only the one ormore abrasive elements 138 exposed (non-coated) along the distal portionof the drive shaft 136. In alternative embodiments, the distal stabilityelement 140 is not covered with the coating, and thus would be exposedlike the abrasive elements 138. In some embodiments, two or more layersof the coating can be included on portions of the drive shaft 136.Further, in some embodiments different coating materials (e.g., withdifferent durometers and/or stiffnesses) can be used at differentlocations on the drive shaft 136.

In the depicted embodiment, the distal stability element 140 is ametallic cylindrical member having an inner diameter that surrounds aportion of the outer diameter of the drive shaft 136. In someembodiments, the distal stability element 140 has a longitudinal lengththat is greater than a maximum exterior diameter of the distal stabilityelement 140. In the depicted embodiment, the distal stability element140 is coaxial with the longitudinal axis of the drive shaft 136.Therefore, the center of mass of the distal stability element 140 isaxially aligned (non-eccentric) with the longitudinal axis of the driveshaft 136. In alternative rotational atherectomy device embodiments,stability element(s) that have centers of mass that are eccentric inrelation to the longitudinal axis may be included in addition to, or asan alternative to, the coaxial stability elements 140. For example, insome alternative embodiments, the stability element(s) can have centersof mass that are eccentric in relation to the longitudinal axis and thatare offset 180 degrees (or otherwise oriented) in relation to the centerof mass of the one or more abrasive elements 138.

The distal stability element 140 may be made of a suitable biocompatiblematerial, such as a higher-density biocompatible material. For example,in some embodiments the distal stability element 140 may be made ofmetallic materials such as stainless steel, tungsten, molybdenum,iridium, cobalt, cadmium, and the like, and alloys thereof. The distalstability element 140 has a fixed outer diameter. That is, the distalstability element 140 is not an expandable member in the depictedembodiment. The distal stability element 140 may be mounted to thefilars of the drive shaft 136 using a biocompatible adhesive, bywelding, by press fitting, and the like, and by combinations thereof.The coating may also be used in some embodiments to attach or tosupplement the attachment of the distal stability element 140 to thefilars of the drive shaft 136. Alternatively, the distal stabilityelement 140 can be integrally formed as a unitary structure with thefilars of the drive shaft 136 (e.g., using filars of a different size ordensity, using filars that are double-wound to provide multiple filarlayers, or the like). The maximum outer diameter of the distal stabilityelement 140 may be smaller than the maximum outer diameters of the oneor more abrasive elements 138.

In some embodiments, the distal stability element 140 has an abrasivecoating on its exterior surface. For example, in some embodiments adiamond coating (or other suitable type of abrasive coating) is disposedon the outer surface of the distal stability element 140. In some cases,such an abrasive surface on the distal stability element 140 can helpfacilitate the passage of the distal stability element 140 throughvessel restrictions (such as calcified areas of a blood vessel).

In some embodiments, the distal stability element 140 has an exteriorcylindrical surface that is smoother and different from an abrasiveexterior surface of the one or more abrasive elements 138. That may bethe case whether or not the distal stability element 140 have anabrasive coating on its exterior surface. In some embodiments, theabrasive coating on the exterior surface of the distal stability element140 is rougher than the abrasive surfaces on the one or more abrasiveelements 138.

Still referring to FIG. 1, the one or more abrasive elements 138 (whichmay also be referred to as a burr, multiple burrs, or (optionally) ahelical array of burrs) can comprise a biocompatible material that iscoated with an abrasive media such as diamond grit, diamond particles,silicon carbide, and the like. In the depicted embodiment, the abrasiveelements 138 includes a total of five discrete abrasive elements thatare spaced apart from each other. In some embodiments, one, two, three,four, five, six, seven, eight, nine, ten, eleven, twelve, thirteen,fourteen, fifteen, or more than fifteen discrete abrasive elements areincluded as the one or more abrasive elements 138. Each of the fivediscrete abrasive elements can include the abrasive media coating, suchas a diamond grit coating.

In the depicted embodiment, the two outermost abrasive elements aresmaller in maximum diameter than the three inner abrasive elements. Insome embodiments, all of the abrasive elements are the same size. Inparticular embodiments, three or more different sizes of abrasiveelements are included. Any and all such possible arrangements of sizesof abrasive elements are envisioned and within the scope of thisdisclosure.

Also, in the depicted embodiment, the center of mass of each abrasiveelement 138 is offset from the longitudinal axis of the drive shaft 136.Therefore, as the eccentric one or more abrasive elements 138 arerotated (along an orbital path), at least a portion of the abrasivesurface of the one or more abrasive elements 138 can make contact withsurrounding stenotic lesion material. As with the distal stabilityelement 140, the eccentric one or more abrasive elements 138 may bemounted to the filars of the torque-transmitting coil of the drive shaft136 using a biocompatible adhesive, high temperature solder, welding,press fitting, and the like. In some embodiments, a hypotube is crimpedonto the drive shaft and an abrasive element is laser welded to thehypotube. Alternatively, the one or more abrasive elements 138 can beintegrally formed as a unitary structure with the filars of the driveshaft 136 (e.g., using filars that are wound in a different pattern tocreate an axially offset structure, or the like).

In some embodiments, the spacing of the distal stability element 140relative to the one or more abrasive elements 138 and the length of thedistal extension portion 142 can be selected to advantageously provide astable and predictable rotary motion profile during high-speed rotationof the drive shaft 136. For example, in embodiments that include thedistal drive shaft extension portion 142, the ratio of the length of thedistal drive shaft extension 142 to the distance between the centers ofthe one or more abrasive elements 138 and the distal stability element140 is about 1:0.5, about 1:0.8, about 1:1, about 1.1:1, about 1.2:1,about 1.5:1, about 2:1, about 2.5:1, about 3:1, or higher than 3:1.

Still referring to FIG. 1, the rotational atherectomy system 100 alsoincludes the actuator handle assembly 110. The actuator handle assembly110 includes a housing and a carriage assembly. The carriage assembly isslidably translatable along the longitudinal axis of the handle assembly110 as indicated by the arrow 115. For example, in some embodiments thecarriage assembly can be translated, without limitation, about 8 cm toabout 12 cm, or about 6 cm to about 10 cm, or about 4 cm to about 8 cm,or about 6 cm to about 14 cm. As the carriage assembly is translated inrelation to the housing, the drive shaft 136 translates in relation tothe sheath 132 in a corresponding manner.

In the depicted embodiment, the carriage assembly includes a valveactuator. In some embodiments, an electric motor for driving rotationsof the drive shaft 136 is coupled to the carriage assembly such that thevalve actuator is an electrical switch instead. In the depictedembodiment, the valve actuator is a button that can be depressed toactuate a compressed gas control valve (on/off; defaulting to off)mounted to the carriage assembly. While the valve actuator is depressed,a compressed gas (e.g., air, nitrogen, etc.) is supplied through thevalve to a turbine member that is rotatably coupled to the carriageassembly and fixedly coupled to the drive shaft 136. Hence, anactivation of the valve actuator will result in a rotation of theturbine member and, in turn, the drive shaft 136 (as depicted by arrow137). In some embodiments, the rotational atherectomy system 100 isconfigured to rotate the drive shaft 136 at a high speed of rotation(e.g., 20,000-160,000 rpm) such that the eccentric one or more abrasiveelements 138 revolve in an orbital path to thereby contact and removeportions of a target lesion (even those portions of the lesion that arespaced farther from the axis of the drive shaft 136 than the maximumradius of the one or more abrasive elements 138).

To operate the handle assembly 110 during a rotational atherectomyprocedure, a clinician can grasp the carriage assembly and depress thevalve actuator with the same hand. The clinician can move (translate)the carriage assembly distally and proximally by hand (e.g., back andforth in relation to the housing), while maintaining the valve actuatorin the depressed state. In that manner, a target lesion(s) can beablated radially and longitudinally by virtue of the resulting orbitalrotation and translation of the one or more abrasive elements 138,respectively.

During an atherectomy treatment, in some cases the guidewire 134 is leftin position in relation to the drive shaft 136 generally as shown. Forexample, in some cases the portion of the guidewire 134 that isextending beyond the distal end of the drive shaft 136 (or extensionportion 142) is about 4 inches to about 8 inches (about 10 cm to about20 cm), about 8 inches to about 12 inches (about 20 cm to about 30 cm),about 4 inches to about 16 inches (about 10 cm to about 40 cm), or about2 inches to about 20 inches (about 5 cm to about 50 cm). In some cases,the guidewire 134 is pulled back to be within (while not extendingdistally from) the drive shaft 136 during an atherectomy treatment. Thedistal end of the guidewire 134 may be positioned anywhere within thedrive shaft 136 during an atherectomy treatment. In some cases, theguidewire 134 may be completely removed from within the drive shaftduring an atherectomy treatment. The extent to which the guidewire 134is engaged with the drive shaft 136 during an atherectomy treatment mayaffect the size of the orbital path of the one or more abrasive elements138.

In the depicted embodiment, the handle assembly 110 also includes aguidewire detention mechanism 118. The guidewire detention mechanism 118can be selectively actuated (e.g., rotated) to releasably clamp andmaintain the guidewire 134 in a stationary position relative to thehandle assembly 110 (and, in turn, stationary in relation to rotationsof the drive shaft 136 during an atherectomy treatment). While the driveshaft 136 and handle assembly 110 are being advanced over the guidewire134 to put the one or more abrasive elements 138 into a targetedposition within a patient's graft 32, the guidewire detention mechanism118 will be unactuated so that the handle assembly 110 is free to slidein relation to the guidewire 134. Then, when the clinician is ready tobegin the atherectomy treatment, the guidewire detention mechanism 118can be actuated to releasably detain/lock the guidewire 134 in relationto the handle assembly 110. That way the guidewire 134 will not rotatewhile the drive shaft 136 is rotating, and the guidewire 134 will nottranslate while the carriage assembly is being manually translated.

Still referring to FIG. 1, the rotational atherectomy system 100 alsoincludes the controller 150. In the depicted embodiment, the controller150 includes a user interface that includes a plurality of selectableinputs that correspond to a plurality of vessel sizes (diameters). Tooperate the rotational atherectomy system 100, the user can select aparticular one of the selectable inputs that corresponds to the diameterof the vessel being treated. In response, the controller 150 willdetermine the appropriate gas pressure for rotating the drive shaft 136in a vessel of the selected diameter (faster rpm for larger vessels andslower rpm for smaller vessel), and supply the gas at the appropriatepressure to the handle assembly 110.

In some embodiments, the controller 150 is pole-mounted. The controller150 can be used to control particular operations of the handle assembly110 and the drive shaft assembly 130. For example, the controller 150can be used to compute, display, and adjust the rotational speed of thedrive shaft 136.

In some embodiments, the controller 150 can include electronic controlsthat are in electrical communication with a turbine RPM sensor locatedon the carriage assembly. The controller 150 can convert the signal(s)from the sensor into a corresponding RPM quantity and display the RPM onthe user interface. If a speed adjustment is desired, the clinician canincrease or decrease the rotational speed of the drive shaft 136. Inresult, a flow or pressure of compressed gas supplied from thecontroller 150 to the handle assembly 110 (via the cable assembly 160)will be modulated. The modulation of the flow or pressure of thecompressed gas will result in a corresponding modulation of the RPM ofthe turbine member and of the drive shaft 136.

In some embodiments, the controller 150 includes one or more interlockfeatures that can enhance the functionality of the rotationalatherectomy system 100. In one such example, if the controller 150 doesnot detect any electrical signal (or a proper signal) from the turbineRPM sensor, the controller 150 can discontinue the supply of compressedgas. In another example, if a pressure of a flush liquid supplied to thesheath 132 is below a threshold pressure value, the controller 150 candiscontinue the supply of compressed gas.

Still referring to FIG. 1, the rotational atherectomy system 100 caninclude an electric handle with an electric motor. In some embodiments,the electric handle can include a user interface that includes aplurality of selectable inputs that correspond to a plurality of vesselsizes (diameters). To operate the rotational atherectomy system 100, theuser can select a particular one of the selectable inputs thatcorresponds to the diameter of the vessel being treated. In response,the electric handle will determine the appropriate rpm for rotating thedrive shaft 136 in a vessel of the selected diameter (faster rpm forlarger vessels and slower rpm for smaller vessel), and operate theelectric motor accordingly.

Referring to FIG. 6, the rotational atherectomy system 100 also includesthe controller 150. In the depicted embodiment, the controller 150includes a user interface that includes a plurality of selectable inputsthat correspond to a plurality of graft sizes (diameters). Other typesof user interfaces are also envisioned. To operate the rotationalatherectomy system 100, the user can select a particular one of theselectable inputs that corresponds to the diameter of the graft beingtreated. In response, the controller 150 will determine the appropriategas pressure for rotating the one or more abrasive elements 138 in agraft of the selected diameter (faster RPM for larger grafts and slowerRPM for smaller grafts), and supply the gas at the appropriate pressureto the handle assembly 110. In some embodiments, the driver for rotationof the one or more abrasive elements 138 is an electrical motor ratherthan the pneumatic motor included in the depicted example. In thedepicted example, the graft 32 to be treated is in a leg 16 of apatient. In particular, the graft 32 is above a knee (e.g., between afemoral artery and a saphenous vein, without limitation).

In some embodiments, the user interface is configured such that the usercan simply select either “LOW,” “MED,” or “HIGH” speed via theselectable inputs. Based on the user's selection of either “LOW,” “MED,”or “HIGH,” the controller 150 will provide a corresponding output forrotating the drive shaft at a corresponding rotational speed. It shouldbe understood that the user interfaces are merely exemplary andnon-limiting. That is, other types of user interface controls can alsobe suitably used, and are envisioned within the scope of thisdisclosure.

Referring to FIGS. 7-13, the rotational atherectomy system 100 can beused to treat a graft 32 having a stenotic lesion 40 along an inner wall38 of the graft 32. The rotational atherectomy system 100 is used tofully or partially remove the stenotic lesion 40, thereby removing orreducing the blockage within the graft 32 caused by the stenotic lesion40. By performing such a treatment, the blood flow through the graft 32may be thereafter increased or otherwise improved. The graft 32 andlesion 40 are shown in longitudinal cross-sectional views to enablevisualization of the rotational atherectomy system 100.

Briefly, in some implementations the following activities may occur toachieve the deployed arrangement shown in FIGS. 7-13. In someembodiments, an introducer sheath (not shown) can be percutaneouslyadvanced into the vasculature of the patient. The guidewire 134 can thenbe inserted through a lumen of the introducer sheath and navigatedwithin the patient's graft 32 to a target location (e.g., the locationof the lesion 40). Techniques such as x-ray fluoroscopy or ultrasonicimaging may be used to provide visualization of the guidewire 134 andother atherectomy system components during placement. In someembodiments, no introducer sheath is used and the guidewire 134 isinserted without assistance from a sheath.

Next, portions of the rotational atherectomy system 100 can be insertedover the guidewire 134. For example, an opening to the lumen of thedrive shaft 136 at the distal free end of the drive shaft 136 (e.g., atthe distal end of the optional distal drive shaft extension portion 142)can be placed onto the guidewire 134, and then the drive shaft assembly130 and handle assembly 110 can be gradually advanced over the guidewire134 to the position in relation to the lesion 40. In some cases, thedrive shaft 136 is disposed fully within the lumen of the sheath 132during the advancing. In some cases, a distal end portion of the driveshaft 136 extends from the distal end opening 143 of the sheath 132during the advancing. Eventually, after enough advancing, the proximalend of the guidewire 134 will extend proximally from the handle assembly110 (via the access port 120 defined by the handle housing).

In some cases (such as in the depicted example), the lesion 40 may be solarge (i.e., so extensively occluding the vessel 10) that it isdifficult or impossible to push the distal stability element 140 throughthe lesion 40. In some such cases, an abrasive outer surface on thedistal stability element 140 can be used to help facilitate passage ofthe distal stability element 140 into or through the lesion 40. In somesuch cases, the drive shaft 136 can be rotated to further helpfacilitate the distal stability element 140 to bore into/through thelesion 40.

Next, as depicted by FIGS. 11-13, the rotation and translational motionsof the drive shaft 136 (and the one or more abrasive elements 138) canbe commenced to perform ablation of the lesion 40.

In some implementations, prior to the ablation of the lesion 40 by theone or more abrasive elements 138, an inflatable member can be used asan angioplasty balloon to treat the lesion 40. That is, an inflatablemember (on the sheath 132, for example) can be positioned within thelesion 40 and then inflated to compress the lesion 40 against the innerwall 38 of the graft 32. Thereafter, the rotational atherectomyprocedure can be performed. In some implementations, such an inflatablemember can be used as an angioplasty balloon after the rotationalatherectomy procedure is performed. In some implementations,additionally or alternatively, a stent can be placed at lesion 40 usingan inflatable member on the sheath 132 (or another balloon memberassociated with the drive shaft assembly 130) after the rotationalatherectomy procedure is performed.

The guidewire 134 may remain extending from the distal end of the driveshaft 136 during the atherectomy procedure as shown. For example, asdepicted by FIGS. 11-13, the guidewire 134 extends through the lumen ofthe drive shaft 136 and further extends distally of the distal end ofthe distal extension portion 142 during the rotation and translationalmotions of the drive shaft 136 (refer, for example, to FIGS. 11-13). Insome alternative implementations, the guidewire 134 is withdrawncompletely out of the lumen of the drive shaft 136 prior to during therotation and translational motions of the drive shaft 136 for abradingthe lesion 40. In other implementations, the guidewire 134 is withdrawnonly partially. That is, in some implementations a portion of theguidewire 134 remains within the lumen of the drive shaft 136 duringrotation of the drive shaft 136, but remains only in a proximal portionthat is not subject to the significant orbital path in the area of theone or more abrasive elements 138 (e.g., remains within the portion ofthe drive shaft 136 that remains in the sheath 132).

To perform the atherectomy procedure, the drive shaft 136 is rotated ata high rate of rotation (e.g., 20,000-160,000 rpm) such that theeccentric one or more abrasive elements 138 revolve in an orbital pathabout an axis of rotation and thereby contacts and removes portions ofthe lesion 40.

Still referring to FIGS. 11-13, the rotational atherectomy system 100 isdepicted during the high-speed rotation of the drive shaft 136. Thecentrifugal force acting on the eccentrically weighted one or moreabrasive elements 138 causes the one or more abrasive elements 138 toorbit in an orbital path around the axis of rotation 139. In someimplementations, the orbital path can be somewhat similar to the orbitalmotion of a “jump rope.” As shown, some portions of the drive shaft 136(e.g., a portion that is just distal of the sheath 132 and anotherportion that is distal of the distal stability element 140) can remainin general alignment with the axis of rotation 139, but the particularportion of the drive shaft 136 adjacent to the one or more abrasiveelements 138 is not aligned with the axis of rotation 139 (and insteadorbits around the axis 139). As such, in some implementations, the axisof rotation 139 may be aligned with the longitudinal axis of a proximalpart of the drive shaft 136 (e.g., a part within the distal end of thesheath 132) and with the longitudinal axis of the distal extensionportion 142 of the drive shaft 136.

In some implementations, as the one or more abrasive elements 138rotates, the clinician operator slowly advances the carriage assemblydistally (and, optionally, reciprocates both distally and proximally) ina longitudinal translation direction so that the abrasive surface of theone or more abrasive elements 138 scrapes against additional portions ofthe occluding lesion 40 to reduce the size of the occlusion, and tothereby improve the blood flow through the graft 32. This combination ofrotational and translational motion of the one or more abrasive elements138 is depicted by the sequence of FIGS. 11-13.

In some embodiments, the sheath 132 may define one or more lumens (e.g.,the same lumen as, or another lumen than, the lumen in which the driveshaft 136 is located) that can be used for aspiration (e.g., of abradedparticles of the lesion 40). In some cases, such lumens can beadditionally or alternatively used to deliver perfusion and/ortherapeutic substances to the location of the lesion 40, or to preventbackflow of blood from graft 32 into sheath 132.

Referring to FIG. 14, a distal end portion of the drive shaft 136 isshown in a longitudinal cross-sectional view. The distal end portion ofthe drive shaft 136 includes the one or more abrasive elements 138 thatare eccentrically-fixed to the drive shaft 136, the distal stabilityelement 140 with an abrasive outer surface, and the distal drive shaftextension portion 142.

In the depicted embodiment, the one or more abrasive elements 138includes a total of five discrete abrasive elements that are spacedapart from each other. In some embodiments, one, two, three, four, five,six, seven, eight, nine, ten, eleven, twelve, thirteen, fourteen,fifteen, or more than fifteen discrete abrasive elements are included asthe one or more abrasive elements 138. Each of the five discreteabrasive elements can include the abrasive media coating.

In the depicted embodiment, the two outermost abrasive elements of theabrasive elements 138 are smaller in maximum diameter than the threeinner abrasive elements of the abrasive elements 138. In someembodiments, all of the abrasive elements are the same size. Inparticular embodiments, three or more different sizes of abrasiveelements 138 are included. Any and all such possible arrangements ofsizes of abrasive elements 138 are envisioned and within the scope ofthis disclosure.

The one or more abrasive elements 138 can be made to any suitable size.For clarity, the size of the one or more abrasive elements 138 willrefer herein to the maximum outer diameter of individual abrasiveelements of the one or more abrasive elements 138. In some embodiments,the one or more abrasive elements 138 are about 2 mm in size (maximumouter diameter). In some embodiments, the size of the one or moreabrasive elements 138 is in a range of about 1.5 mm to about 2.5 mm, orabout 1.0 mm to about 3.0 mm, or about 0.5 mm to about 4.0 mm, withoutlimitation. Again, in a single embodiment, one or more of the abrasiveelements 138 can have a different size in comparison to the otherabrasive elements 138. In some embodiments, the two outermost abrasiveelements are about 1.5 mm in diameter and the inner abrasive elementsare about 2.0 mm in diameter.

In the depicted embodiment, the one or more abrasive elements 138,individually, are oblong in shape. A variety of different shapes can beused for the one or more abrasive elements 138. For example, in someembodiments the one or more abrasive elements 138 are individuallyshaped as spheres, discs, rods, cylinders, polyhedrons, cubes, prisms,and the like. In some embodiments, such as the depicted embodiment, allof the one or more abrasive elements 138 are the same shape. Inparticular embodiments, one or more of the abrasive elements 138 has adifferent shape than one or more of the other abrasive elements 138.That is, two, three, or more differing shapes of individual abrasiveelements 138 can be combined on the same drive shaft 136.

In the depicted embodiment, adjacent abrasive elements of the one ormore abrasive elements 138 are spaced apart from each other. Forexample, in the depicted embodiment the two distal-most individualabrasive elements are spaced apart from each other by a distance ‘X’. Insome embodiments, the spacing between adjacent abrasive elements isconsistent between all of the one or more abrasive elements 138.Alternatively, in some embodiments the spacing between some adjacentpairs of abrasive elements differs from the spacing between otheradjacent pairs of abrasive elements.

In some embodiments, the spacing distance X in ratio to the maximumdiameter of the abrasive elements 138 is about 1:1. That is, the spacingdistance X is about equal to the maximum diameter. The spacing distanceX can be selected to provide a desired degree of flexibility of theportion of the drive shaft 136 to which the one or more abrasiveelements 138 are attached. In some embodiments, the ratio is about 1.5:1(i.e., X is about 1.5 times longer than the maximum diameter). In someembodiments, the ratio is in a range of about 0.2:1 to about 0.4:1, orabout 0.4:1 to about 0.6:1, or about 0.6:1 to about 0.8:1, or about0.8:1 to about 1:1, or about 1:1 to about 1.2:1, or about 1.2:1 to about1.4:1, or about 1.4:1 to about 1.6:1, or about 1.6:1 to about 1.8:1, orabout 1.8:1 to about 2.0:1, or about 2.0:1 to about 2.2:1, or about2.2:1 to about 2.4:1, or about 2.4:1 to about 3.0:1, or about 3.0:1 toabout 4.0:1, and anywhere between or beyond those ranges.

In the depicted embodiment, the center of mass of each one of the one ormore abrasive elements 138 is offset from the longitudinal axis of thedrive shaft 136 along a same radial angle. Said another way, the centersof mass of all of the one or more abrasive elements 138 are coplanarwith the longitudinal axis of the drive shaft 136. If the size of eachof the one or more abrasive elements 138 is equal, the centers of massof the one or more abrasive elements 138 would be collinear on a linethat is parallel to the longitudinal axis of the drive shaft 136.

Referring to FIG. 15, according to some embodiments of the rotationalatherectomy devices provided herein, one or more abrasive elements 144are arranged at differing radial angles in relation to the drive shaft136. In such a case, a path defined by the centers of mass of the one ormore abrasive elements 144 spirals along the drive shaft 136. In somecases (e.g., when the diameters of the one or more abrasive elements 144are equal and the adjacent abrasive elements are all equally spaced),the centers of mass of the one or more abrasive elements 144 define ahelical path along/around the drive shaft 136. It has been found thatsuch arrangements can provide a desirably-shaped orbital rotation of theone or more abrasive elements 144.

It should be understood that any of the structural features described inthe context of one embodiment of the rotational atherectomy devicesprovided herein can be combined with any of the structural featuresdescribed in the context of one or more other embodiments of therotational atherectomy devices provided herein. For example, the sizeand/or shape features of the one or more abrasive elements 138 can beincorporated in any desired combination with the spiral arrangement ofthe one or more abrasive elements 144.

Referring also to FIGS. 16-20, the differing radial angles of theindividual abrasive elements 144 a, 144 b, 144 c, 144 d, and 144 e canbe further visualized. To avoid confusion, each figure of FIGS. 17-21illustrates only the closest one of the individual abrasive elements 144a, 144 b, 144 c, 144 d, and 144 e (i.e., closest in terms of thecorresponding cutting-plane as shown in FIG. 16). For example, in FIG.17, abrasive element 144 b is shown, but abrasive element 144 a is notshown (so that the radial orientation of the abrasive element 144 b isclearly depicted).

It can be seen in FIGS. 16-20 that the centers of mass of abrasiveelements 144 a, 144 b, 144 c, 144 d, and 144 e are at differing radialangles in relation to the drive shaft 136. Hence, it can be said thatthe abrasive elements 144 a, 144 b, 144 c, 144 d, and 144 e are disposedat differing radial angles in relation to the drive shaft 136.

In the depicted embodiment, the radial angles of the abrasive elements144 a, 144 b, 144 c, 144 d, and 144 e differ from each other by aconsistent 37.5 degrees (approximately) in comparison to the adjacentabrasive element(s). For example, the center of mass of abrasive element144 b is disposed at a radial angle B that is about 37.5 degreesdifferent than the angle at which the center of mass of abrasive element144 a is disposed, and about 37.5 degrees different than the angle C atwhich the center of mass of abrasive element 144 c is disposed.Similarly, the center of mass of abrasive element 144 c is disposed at aradial angle C that is about 37.5 degrees different than the angle B atwhich the center of mass of abrasive element 144 b is disposed, andabout 37.5 degrees different than the angle D at which the center ofmass of abrasive element 144 d is disposed. The same type of relativerelationships can be said about abrasive element 144 d.

While the depicted embodiment has a relative radial offset of 37.5degrees (approximately) in comparison to the adjacent abrasiveelement(s), a variety of other relative radial offsets are envisioned.For example, in some embodiments the relative radial offsets of theadjacent abrasive elements is in a range of about 0 degrees to about 5degrees, or about 5 degrees to about 10 degrees, or about 10 degrees toabout 15 degrees, or about 15 degrees to about 20 degrees, or about 20degrees to about 25 degrees, or about 25 degrees to about 30 degrees, orabout 30 degrees to about 35 degrees, or about 10 degrees to about 30degrees, or about 20 degrees to about 40 degrees, or about 20 degrees toabout 50 degrees.

While in the depicted embodiment, the relative radial offsets of theabrasive elements 144 a, 144 b, 144 c, 144 d, and 144 e in comparison tothe adjacent abrasive element(s) are consistent, in some embodimentssome abrasive elements are radially offset to a greater or lesser extentthan others. For example, while angles B, C, D, and E are all multiplesof 37.5 degrees, in some embodiments one or more of the angles B, C, D,and/or E is not a multiple of the same angle as the others.

The direction of the spiral defined by the centers of mass of theabrasive elements 144 a, 144 b, 144 c, 144 d, and 144 e can be in eitherdirection around the drive shaft 136, and in either the same directionas the wind of the filars or in the opposing direction as the wind ofthe filars.

A number of embodiments of the invention have been described.Nevertheless, it will be understood that various modifications may bemade without departing from the spirit and scope of the invention. Forexample, design features of the embodiments described herein can becombined with other design features of other embodiments describedherein. Accordingly, other embodiments are within the scope of thefollowing claims.

What is claimed is:
 1. A method for performing rotational atherectomy toremove stenotic lesion material from an arteriovenous graft of apatient, the method comprising: delivering a rotational atherectomydevice into the arteriovenous graft, wherein the rotational atherectomydevice comprises: an elongate flexible drive shaft comprising atorque-transmitting coil and defining a longitudinal axis, the driveshaft being configured to rotate about the longitudinal axis; and ahelical array of abrasive elements attached to a distal end portion ofthe drive shaft, each of the abrasive elements having a center of massthat is offset from the longitudinal axis, the centers of mass of theabrasive elements arranged along a path that spirals around thelongitudinal axis; rotating the drive shaft about the longitudinal axissuch that the abrasive elements orbit around the longitudinal axis;rotating a distal cylindrical metallic element concentrically andfixedly attached to the distal end portion of the drive shaft at aposition distal of the helical array of abrasive elements; rotating thedistal cylindrical metallic element so that an abrasive outer coating ofthe distal cylindrical metallic element engages the stenotic lesionmaterial and defines an initial abrading path through the stenoticlesion material in the synthetic arteriovenous graft; and after theinitial abrading path is defined by the distal cylindrical metallicelement, translationally moving the drive shaft in a longitudinaldirection within an interior of the arteriovenous graft simultaneouslywith said rotating the drive shaft so that the helical array of abrasiveelements remove the stenotic lesion material from the interior of thearteriovenous graft while the abrasive elements travel in thearteriovenous graft in an orbital path having an orbit diameter multipletimes greater than an outer maximum diameter of each of the abrasiveelements.
 2. A method for performing rotational atherectomy to removestenotic lesion material from a synthetic arteriovenous graftinterconnected to an artery and a vein of a patient, the methodcomprising: delivering a rotational atherectomy device into thesynthetic arteriovenous graft, wherein the rotational atherectomy devicecomprises: an elongate flexible drive shaft comprising atorque-transmitting coil and defining a longitudinal axis, the driveshaft being configured to rotate about the longitudinal axis; and firstand second abrasive elements attached to a distal end portion of thedrive shaft and each having a center of mass offset from thelongitudinal axis, the center of mass of the first abrasive elementbeing offset from the longitudinal axis in a first longitudinal plane,the center of mass of the second abrasive element being offset from thelongitudinal axis in a second longitudinal plane that differs from thefirst longitudinal plane and that is oriented at a radial angle relativeto the first longitudinal plane; a distal concentric metallic elementhaving an abrasive outer coating and is fixedly and concentricallyattached to the distal end portion of the drive shaft at a positiondistally of the first and second abrasive elements so that the distalconcentric metallic element has a center of mass aligned with thelongitudinal axis; and rotating the drive shaft about the longitudinalaxis such that the abrasive elements orbit around the longitudinal axisto remove the stenotic lesion material from the interior of thesynthetic arteriovenous graft.
 3. The method of claim 2, furthercomprising: rotating the distal concentric metallic element so that theabrasive outer coating of the distal cylindrical metallic elementengages the stenotic lesion material and the distal concentric metallicelement defines an initial abrading path through the stenotic lesionmaterial in the synthetic arteriovenous graft; and after the initialabrading path is defined by the distal concentric metallic element,translationally moving the drive shaft in a longitudinal directionwithin an interior of the arteriovenous graft simultaneously with saidrotating the drive shaft so that the helical array of abrasive elementsremove the stenotic lesion material from the interior of thearteriovenous graft while the abrasive elements travel in thearteriovenous graft in an orbital path having an orbit diameter multipletimes greater than an outer maximum diameter of each of the first andsecond abrasive elements.
 4. The method of claim 2, further comprisingmodifying a speed of the drive shaft.
 5. The method of claim 4, whereinmodifying the speed of the drive shaft modifies a diameter of rotation.6. The method of claim 2, wherein delivering the rotational atherectomydevice comprises delivering the rotational atherectomy device with adistal portion of the rotational atherectomy device positioned toward avein of the patient.
 7. The method of claim 2, wherein delivering therotational atherectomy device comprises delivering the rotationalatherectomy device with a distal portion of the rotational atherectomydevice positioned toward an artery of the patient to treat a lesion atan arterial anastomosis.
 8. The method of claim 2, further comprisinginflating an inflatable member on the rotational atherectomy device. 9.The method of claim 2, further comprising a distal stability elementfixedly mounted to the drive shaft and having a center of mass alignedwith the longitudinal axis, the distal stability element being distallyspaced apart from the first and second abrasive elements.
 10. A methodfor performing rotational atherectomy to remove stenotic lesion materialfrom an arteriovenous graft of a patient, the method comprising:delivering a rotational atherectomy device into the arteriovenous graft,wherein the rotational atherectomy device comprises: an elongateflexible drive shaft comprising a torque-transmitting coil and defininga longitudinal axis, the drive shaft being configured to rotate aboutthe longitudinal axis; and a helical array of abrasive elements attachedto a distal end portion of the drive shaft, each of the abrasiveelements having a center of mass that is offset from the longitudinalaxis, the centers of mass of the abrasive elements arranged along a paththat spirals around the longitudinal axis; rotating the drive shaftabout the longitudinal axis such that the abrasive elements orbit aroundthe longitudinal axis; and rotating a distal cylindrical metallicelement concentrically and fixedly attached to the distal end portion ofthe drive shaft at a position distal of the helical array of abrasiveelements; wherein the arteriovenous graft comprises a syntheticarteriovenous graft interconnected to an artery and a vein in an arm ofthe patient, and the helical array of abrasive elements comprises fivespherical abrasive elements spaced apart from one another, wherein acentral abrasive element of the five spherical abrasive elements has amaximum outer diameter that is greater than or equal to a maximum outerdiameter of a proximal-most abrasive element and a distal-most abrasiveelement of the five spherical abrasive elements, and wherein therotational atherectomy device further comprises the distal cylindricalmetallic element having an abrasive outer coating attachedconcentrically to the distal end portion of the drive shaft at aposition distally of the helical array of abrasive elements so that thedistal cylindrical metallic element has a center of mass aligned withthe longitudinal axis.
 11. The method of claim 10, wherein the fivespherical abrasive elements of the helical array of abrasive elementsare spaced apart from one another by a spacing distance, and the distalcylindrical metallic element is spaced distally from the distal-mostabrasive element of the helical array of abrasive elements by a lengththat is greater than the spacing distance of the helical array ofabrasive elements.
 12. The method of claim 11, wherein the proximal-mostabrasive element and the distal-most abrasive element of the helicalarray of abrasive elements are smaller in maximum outer diameter thaneach abrasive elements of the helical array of abrasive elementspositioned between the proximal-most abrasive element and thedistal-most abrasive element.
 13. The method of claim 11, wherein thefive spherical abrasive elements of the helical array of abrasiveelements have the same maximum outer diameter.
 14. The method of claim11, wherein a ratio of the spacing distance of the five sphericalabrasive elements to the maximum outer diameter of the central abrasiveelement is 0.8:1 to 1:1.
 15. The method of claim 11, wherein the fivespherical abrasive elements each have a maximum outer diameter in arange of 1.0 mm to 3.0 mm.
 16. The method of claim 15, furthercomprising: rotating the distal cylindrical metallic element so that theabrasive outer coating of the distal cylindrical metallic elementengages the stenotic lesion material during an initial path through thestenotic lesion material in the synthetic arteriovenous graft; and afterthe initial path through the stenotic lesion material, translationallymoving the drive shaft in a longitudinal direction within an interior ofthe arteriovenous graft simultaneously with said rotating the driveshaft so that the helical array of abrasive elements remove the stenoticlesion material from the interior of the arteriovenous graft while theabrasive elements travel in the arteriovenous graft in an orbital path.17. A method for performing rotational atherectomy to remove stenoticlesion material from an arteriovenous graft of a patient, the methodcomprising: delivering a rotational atherectomy device into thearteriovenous graft, wherein the rotational atherectomy devicecomprises: an elongate flexible drive shaft comprising atorque-transmitting coil and defining a longitudinal axis, the driveshaft being configured to rotate about the longitudinal axis; and ahelical array of abrasive elements attached to a distal end portion ofthe drive shaft, each of the abrasive elements having a center of massthat is offset from the longitudinal axis, the centers of mass of theabrasive elements arranged along a path that spirals around thelongitudinal axis; rotating the drive shaft about the longitudinal axissuch that the abrasive elements orbit around the longitudinal axis; androtating a distal cylindrical metallic element concentrically andfixedly attached to the distal end portion of the drive shaft at aposition distal of the helical array of abrasive elements; wherein thearteriovenous graft comprises a synthetic arteriovenous graftinterconnected to an artery and a vein in a torso of the patient, andthe helical array of abrasive elements comprises five spherical abrasiveelements spaced apart from one another, wherein a central abrasiveelement of the five spherical abrasive elements has a maximum outerdiameter that is greater than or equal to a maximum outer diameter of aproximal-most abrasive element and a distal-most abrasive element of thefive spherical abrasive elements, and wherein the rotational atherectomydevice further comprises the distal cylindrical metallic element havingan abrasive outer coating attached concentrically to the distal endportion of the drive shaft at a position distally of the helical arrayof abrasive elements so that the distal cylindrical metallic element hasa center of mass aligned with the longitudinal axis.